Various apparatuses, particularly electical and electro-optical apparatuses such as computers, are designed to be operable in a minimum configuration that may be expanded by connection thereto of optional equipment such as option circuit boards. Such apparatuses often require flow past them of substances exhibiting fluid flow characteristics--air or water, for example--for purposes such as cooling or flushing. During hydraulic studies, we have discovered that the addition/removal of the optimal equipment to/from such apparatuses often undesirably affects the hydraulics--the flow patterns--of the substance. For example, an option board-equippable computer designed to exhibit an optimum cooling airflow pattern inside its cabinet when it is fully equipped with option boards typically does not exhibit that pattern--and hence may be inadequately cooled--when it is either wholly or partly unequipped with option circuit boards. It is a problem, therefore, to provide proper and adequate hydraulic flow patterns with respect to such apparatuses. Since an apparatus designer must design for the worst-case configuration of the apparatus, he or she must design for the unequipped configuration.
Often, such apparatuses also undesirably emit acoustic or electromagnetic energy, and it is a problem to limit such emissions.